1. Field of the Invention
This invention relates to battery modules that are installed in portable electronic and telephone devices such as cellular phones, digital cameras, PHS terminals (xe2x80x98PHSxe2x80x99 is an abbreviation for xe2x80x98Portable Handyphone Systemxe2x80x99) and the like. This invention also relates to positioning structures for firmly holding battery modules in prescribed positions within portable electronic telephone devices.
2. Description of the Related Art
Battery modules are conventionally and widely used in portable and electronic telephone devices such as digital cameras, cellular phones, PHS terminals and the like. A typical example of the battery module comprises a battery cell, a circuit board for mounting circuit components for use in charging control, insulation and electrical protection of the battery cell, and a connector providing connection with the main unit of the cellular phone. This was disclosed in various documents such as Japanese Unexamined Patent Publication No. 2000-315483.
The circuit board has terminals that are respectively connected to a positive electrode terminal and a negative electrode terminal of the battery cell, and it is connected with the connector by an exposed harness. The circuit board and the battery cell are integrally formed together with a covering resin material. The battery cell is typically small and light in weight because it is to be installed in a very small space within a cellular phone. In general, the battery cell is designed as a thin plate having a rectangular shape. A pair of opposite side surfaces of the battery cell providing the positive and negative electrode terminals are coated with the resin material. Thus, the battery module is formed by coating areas of the battery cell that contain a pair of opposite side surfaces, with resin.
Forming and shaping of the battery module is made in accordance with shaping characteristics of the battery cell, which is a thin, rectangular plate subjected to resin coating. The general process for producing the battery module contains three steps as follows:
(i) The battery cell is held in a metal mold comprising a plurality of mold members, which can be separated from each other in the thickness direction of the battery cell.
(ii) The resin is caused to flow into the gap formed between the battery cell and the cavity surface of the metal mold.
(iii) The battery module formed with the resin is then separated from the metal mold. That is, when the metal mold is opened, the battery module is held in the cavity of a mold member. An appropriate means, such as an ejector, is used to urge the battery module in its thickness direction, so that the battery module may be extracted or ejected from the metal mold.
In order to simplify the separation of the resin-shaped battery module from the metal mold, so-called xe2x80x98extract slopesxe2x80x99 are provided on side surfaces of the battery module. Generally speaking, an extract slope has a prescribed slope angle, which ranges between approximately 0.5xc2x0 and 2.0xc2x0. These slopes are made very small, so that they may not be visually noticed when viewing the battery module of the thin-plate shape.
The aforementioned battery module should be firmly held in the prescribed space of the cellular phone to avoid unwanted movement thereof while the cellular phone is being carried or transported. That is, the battery module is subjected to positioning such that it is firmly secured and held in a concave or hollow space provided inside the cellular phone.
It is not preferable that a cellular phone employ a complicated positioning structure, causing an increase in the number of parts, the number of assembly steps, and, consequently, the manufacturing cost. Due to the aforementioned small extract slopes being formed on side surfaces of the battery module, it is very difficult to shape the hollow space to match the external configuration of the battery module with a high precision.
If the hollow space is shaped to match the external configuration of the battery module with a high precision, the cellular phone provides a very small clearance for allowing the battery module to be inserted into the hollow space. It will be difficult for an installer to assemble the battery module and to insert it precisely into the hollow space of the cellular phone when the clearance is so small.
It is an object of the invention to provide a battery module which can be easily manufactured at low cost.
It is another object of the invention to provide a positioning structure for positioning and firmly holding the battery module in a prescribed portion within a cellular phone.
A battery module of this invention is produced by coating selected sides of a rectangular, thin-plate battery cell with a prescribed resin material having a low softening temperature and low viscosity in melting, for example, polyamide resin, polyurethane resin, or polyolefin resin. In accordance with the invention, the battery module side surfaces are provided with slopes having the same slope angle of 5xc2x0 or more in the thickness direction. As a result, upper side edges of the battery module are distanced farther apart from each other than its lower side edges. Preferably, the slope angle ranges between 5xc2x0 and 10xc2x0. In addition, it is possible to provide a cover member for entirely covering an upper surface of the battery cell.
A positioning structure is provided in accordance with this invention for establishing the prescribed positioning between the battery module and its counterpart unit such as a compartment of a cellular phone having a hollow space. Slopes are formed along side walls of the hollow space to provide complementary shapes to the sloped module side surfaces. Thus, when the battery module is installed in the hollow space, the sloped module side surfaces slide along and come in close contact with the slopes of the side walls of the hollow space.
Due to the provision of the relatively large slopes to the module side surfaces of the battery module as well as the side walls of the hollow space of the counterpart unit, it is possible to improve the manufacturing process, especially in assembling the battery module and its counterpart unit (i.e., the accommodating part) together.
The above and other objects, aspects, features and advantages of the invention will be more readily apparent from the description of the preferred embodiments thereof taken in conjunction with the accompanying drawings and appended claims.